The present invention relates to a system for remotely measuring the average temperature of hot gases. In particular, the invention relates to hot gases in fired furnaces.
The flue gas temperature in the transition zone between radiant and convection section of a fired furnace (frequently called the Bridgewall temperature) is a relative measure of the heat release in the radiant section. In order to maintain a proper balance of heat release between radiant and convection section and also to protect the metal tubes in the convection section from overheating, one must monitor the flue gas temperature in the transition zone. Generally, this is done by thermocouples at the refractory wall near the transition zone. While this measurement gives some indication of gas temperature, a direct measurement of the flue gas temperature in the transition zone, averaged over the length of the furnace, is preferable.